Quote:
Originally Posted by COLVERT
However if it's jammed, as I mentioned, it's never going to move from where it is now. The gauge on the dash will always read the same.---Taking it out is really the only way, really, to find the fault.-----  |
Nope wrong, sorry !
No matter where the float assembly is, as soon as the ignition is turned off the needle should drop to zero, the stepper motor always returns to zero,its park position, likewise with the rev counter and speedo !
Rather than faffing about dragging the pump / float assembly out to check, the easiest and quickest way to initially diagnose if it is the gauge the dial or other problems is, as I mentioned earlier, to use the onboard diagnostics to cycle all the dials from rest position to full scale, if it passes this, the fault may be somewhere else.
These modern stepper motor instruments work nothing like the old magnetic ones, and even with those, if the float was stuck at say, half full, the gauge would rise to half full with ignition on, regardless of the actual level, due to the current from the resistive path at that point, providing the magnetic field to pull the needle round to that position and hold it there.
However, once the ignition is turned off, there is no current flowing through the resistive path, the magnetic field collapses and the needle is returned to its rest / park position by the hair spring.
Unlike the old gauges, there is no direct connection between the tank sender and the gauge, though both use the same info, varying voltage, in the new systems this voltage is processed and is then sent to the stepper motor to move the needle to the correct position via x number of increments of the motor.
